Credentials include identification cards, driver's licenses, passports, and other documents. Such credentials are formed from credential or card substrates including paper substrates, plastic substrates, cards, and other materials. Such credentials generally include printed information, such as a photo, account numbers, identification numbers, and other personal information. Credentials can also include data that is encoded in a smartcard chip, a magnetic stripe, or a barcode, for example.
Credential production devices include processing devices that process credential substrates by performing at least one processing step in forming a final credential product. Such processes generally include a printing process, a laminating or transfer process, a data reading process, a data writing process, and/or other process used to form the desired credential.
In a printing process, a printing device is used to print an image either directly to the substrate (i.e., direct printing process) or to a print intermediate, from which the image is transferred to the substrate (i.e., reverse-image transfer printing process). Typical printing devices include a thermal print head, which prints an image by heating and transferring dye from a print ribbon, and an ink jet print head.
In a transfer or laminating process, an overlaminate material is transferred to a surface of the card substrate using a transfer device, such as a heated laminating or transfer roller. The overlaminate material may be in the form of a patch laminate or a thin film laminate. The overlaminate material is typically one of two types: a patch laminate, or a fracturable laminate or transfer layer often referred to as a “thin film laminate.” The patch laminate is generally a pre-cut polyester film that has been coated with a thermal adhesive on one side. The transfer roller is used to heat the patch to activate the adhesive, and press the adhesive-coated side of the patch to a surface of a substrate to bond the patch to the surface.
Thin film laminates or transfer layers are fracturable laminates that are generally formed of a continuous resinous material that have been coated onto a carrier layer or backing to form a transfer ribbon. The side of the resin material that is not attached to the continuous carrier layer is generally coated with a thermal adhesive which is used to create a bond between the resin and a surface of a substrate. The transfer roller is used to heat the transfer layer to activate the adhesive and press the adhesive-coated side of the transfer layer against the surface of the substrate to bond the material to the surface. The carrier layer or backing is removed to complete the lamination or transfer process.
The transfer layer or patch laminate may also be in the form of a print intermediate, on which an image may be printed in the reverse-image printing process mentioned above. In the reverse-image printing process, the print head is registered (i.e., aligned) with a print section of the transfer ribbon, and a printing process is performed to print an image on the print section using the print head. Next, the imaged print section is registered with the transfer device and a substrate. The transfer device is then used to perform the transfer or laminating operation described above to bond the imaged print section of the transfer layer or patch laminate to the surface of the card substrate.
Registration of the print sections to the print head, transfer device and substrates, typically involves detecting registration marks on the transfer ribbon that identify the locations of the print sections using an optical sensor. A controller of the credential production device controls the feeding of the transfer ribbon relative to the print head and/or transfer device based on the detection of the registration marks.
Misalignment between the print head and the print section, or between the imaged print section and the transfer device, can result in a defective credential product. Accordingly, it is critical that the registration marks are accurately detected to allow for precise registration of the print sections to the print head during print operations, and to allow for precise registrations of the imaged print sections to the transfer device and substrates during the transfer process. Unfortunately, conventional optical sensors are susceptible to misidentifying non-registration marks, such as portions of an image printed to the transfer ribbon using the print head, as registration marks.